The present invention relates to an analytical aid comprising a lancet and a test element, an analyzer for the analysis of a sample by means of such an analytical aid, and a method for the analysis of a sample with the aid of such an analytical aid.
The examination of blood samples or interstitial fluid makes the early and reliable detection of pathological conditions and the targeted and verified monitoring of states of the body possible in clinical diagnostics. Medical diagnostics requires that a sample of blood or interstitial fluid is first obtained from the individual to be examined.
To obtain a sample, the skin can be perforated, for example at the finger tip or earlobe of the person to be examined, with the aid of a sterile, sharp lancet to obtain just a few microliters or less of blood for the analysis. This method is suitable, in particular, for the analysis of a sample that is carried out immediately or shortly after the sample is obtained.
In the area known as “home monitoring,” medically untrained people can carry out simple analyses of blood or interstitial fluid. In particular, where blood has to be obtained regularly, e.g., several times a day, by diabetics for monitoring blood-glucose concentration, lancets and accompanying devices (known as pricking aids) are available that make it possible for samples to be obtained as painlessly and reproducibly as possible. Such lancets and devices (pricking aids) are, for example, the subject of WO 98/48695, EP 0 656 970, U.S. Pat. No. 4,442,836 and U.S. Pat. No. 5,554,166.
Self-determination of blood-sugar levels is today a globally widespread method of monitoring diabetes. Known blood sugar devices in the art comprise an analyzer into which a test element (test strip) is inserted. The test element is brought into contact with a drop of a sample, which has previously been obtained, for example, from the finger tip by a pricking aid.
The numerous system components (lancet, pricking aid, test element and analyzer) require considerable space and relatively complex handling. Systems also exist having a higher degree of integration, and consequently easier handling. For example, the test elements are stored in the analyzer and made available for measurement. A next step in miniaturization may be achieved, for example, through the integration of several functions or functional elements in a single analytical aid (disposable). For example, the operating sequence can be greatly simplified by suitable combination of the pricking procedure and sensor-based analyte concentration detection on one test element.
DE 103 15 544 relates to a method for producing combined pricking and measuring devices for detecting an analyte in a fluid, which include a support and a detection element. The method comprises the steps of forming recesses which define pricking points on one end face of the support material in strip form, applying a detection element to the support material in strip form and separating individual pricking/measuring disposable base bodies either individually or in groups from the support material at separating lines. The combined pricking and measuring devices can include individual pricking/measuring disposable base bodies which have a pricking point. The pricking point is provided with a soft plastic covering. The base body further includes a detection element, which after sterilizing and/or sealing of the individual pricking/measuring disposable base body, is applied to the latter.
DE 101 42 232 describes an analytical aid with a lancet and a test element. The lancet includes a lancet needle with a point and a lancet body, which completely surrounds the lancet needle, at least in the region of the point, the lancet needle being displaceable in relation to the lancet body. At least in the region of the point of the lancet needle, the lancet body consists of an elastic material, in which the point of the lancet needle is embedded. The analytical test element is fixedly connected to the lancet body.
One way of providing analytical aids encountered in the art is to provide the lancet with a capillary structure or to make it part of a capillary structure. Consequently, after pricking and the emergence of a drop of blood, the lancet point is moved to the blood in order to transport it with the capillary to test chemicals present on a test element. However, this can include several disadvantages.
The lancet point has to be kept sterile until immediately before use. Before use, the sterile protection has to be removed. After removal, it must not hinder the capillary function, but must be moved completely out of the blood path. The sterile protection may need to be removed, which can provide an individual part that is complicated to handle by a machine.
The capillary structure, which at least partially includes the lancet point, must be hydrophilic in order for the blood to be transported. However, up until the lancet is used, the sterile protection must provide a tight seal to prevent germs from getting in. Therefore, intimate contact between the sterile protection and the lancet point or the lancet stem is necessary. This intimate contact can, however, adversely change the surface properties, in particular, the hydrophilia of the lancet.
Once the blood has emerged, the opening of the capillary must directly contact the blood sample in order to be sucked up. There is a risk that the sharp point of the lancet will again prick the tissue. Therefore, exact knowledge of the position of the surface of the skin is required.
The production of analytical aids can include many problems. The lancet has to be sterilized and the sterility of the lancet has to be ensured throughout the time during which the analytical aid can be used. The test chemicals present in the testing area of the test element can be adversely influenced in the way in which they function and act by the known methods of sterilization. Sensitive chemicals or biological substances can be harmed. Therefore, the test chemicals should not be exposed to the sterilization process for the lancet.